2 research outputs found
Near-Field Energy Extraction with Hyperbolic Metamaterials
Although
blackbody radiation described by Planck’s law is commonly regarded
as the maximum of thermal radiation, thermal energy transfer in the
near-field can exceed the blackbody limit due to the contribution
from evanescent waves. Here, we demonstrate experimentally a broadband
thermal energy extraction device based on hyperbolic metamaterials
that can significantly enhance near-field thermal energy transfer.
The thermal extractor made from hyperbolic metamaterials does not
absorb or emit any radiation but serves as a transparent pipe guiding
the radiative energy from the emitter. At the same gap between an
emitter and an absorber, we observe that near-field thermal energy
transfer with thermal extraction can be enhanced by around 1 order
of magnitude, compared to the case without thermal extraction. The
novel thermal extraction scheme has important practical implications
in a variety of technologies, e.g., thermophotovoltaic energy conversion,
radiative cooling, thermal infrared imaging, and heat assisted magnetic
recording
Perfect Thermal Emission by Nanoscale Transmission Line Resonators
Thermal radiation with a narrow-band
emission spectrum is of great importance in a variety of applications
such as infrared sensing, thermophotovoltaics, radiation cooling,
and thermal circuits. Although resonant nanophotonic structures such
as metamaterials and nanocavities have been demonstrated to achieve
the narrow-band thermal emission, maximizing their radiation power
toward perfect emission still remains challenging. Here, based on
the recently developed quasi-normal mode theory, we prove that thermal
emission from a nanoscale transmission line resonator can always be
maximized by tuning the waveguiding loss of the resonator or bending
the structure. By use of nanoscale transmission line resonators as
basic building blocks, we experimentally demonstrate a new type of
macroscopic perfect and tunable thermal emitters. Our experimental
demonstration in conjunction with the general theoretical framework
from the quasi-normal mode theory lays the foundation for designing
tunable narrow-band thermal emitters with applications in thermal
infrared light sources, thermal management, and infrared sensing and
imaging